Sofa



FIG. 1 is a front perspective view showing our new design of a sofa;

FIG. 2 is a front elevational view thereof,

FIG. 3 is a top view thereof,

FIG. 4 is a left side view thereof, the right side view being a mirror image; and,

FIG. 5 is a rear perspective view thereof.

The broken lines shown in the figures are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a sofa, as shown and described. 